Markets: Stone windowpanes

Interesting to note that perforated slabs are becoming ever more popular at stone fairs. Often they are not for sale but part of the aesthetic effect the exhibitor wishes to create – „they quite simply attract clients to our stand“ the exhibitors explain when asked about the presentation. But the marketing potential for the stone branch is enormous.

It is well known that in the entire Islamic world as well as in India these were the forerunners of windowpanes as we know them today. But in European culture they have their place too, as can be seen on the photo of the entrance portal to St. Mark’s Cathedral in Venice probably conceived around 1250 a.D.

The subsequent development was probably closely connected to the spread of glass manufacturing: in the early stages of glass manufacturing, panes could only be produced in small dimensions. This is where the stonemasons came in with their bar tracery portioning the huge windows off into bite-size pieces, so to speak.

It was possible to affix glass panes between bows and stanchions solidly enough to allow any window to withstand a storm. It is interesting to note that the patterns, as diverse as they may be, are always orientated along circular forms.

These windows differ from those in the Arabic world, around the Mediterranean or in Spain where the patterns are square and wooden. Interestingly, there too, patterns follow the rules of geometry – mathematics was very popular since the Arabs had conquered half the globe. Mashrabyia is what these balconies with wooden windows are called in Arabic.

Particularly projecting alcoves are constructed in this manner. The lattice or perforated pattern allows one to look out without being seen. Perforated surfaces were also used indoors to separate men and women. They can be found in the entire Arabic world and became popular in the old caravan series, giving rooms a cool ambience combined with marble floors and rippling fountains. (1, 2).

In Indian culture they can be found as well. The Hawa Mahal or Palace of the Winds in Jaipur is the best known example: the present-day hotel owes its nickname to the pleasant breeze which circulates throughout the rooms. This is made possible without the aid of air conditioners or ventilators thanks to the perforated pattern in the sandstone of its windows. The Red Fort across from the Taj Mahal also has Jali-windows, there made of red sandstone.

Let us note then, throughout the world in many different cultures we find examples of non-glass windows dating back to ancient times. They decorated the facades, made those inside invisible to outsiders and provided optimal air conditioning. Last but not least they lend an air of vitality to the darkened interior rooms through the play with light and shadow.

Considering such diverse marketing possibilities, it seems worthwhile to give a rebirth to the old treasure. The technology for a modern low-cost production is at hand – water-jetting.

Windows are but one of many possible uses: room dividers or vestibules, railings for inside and out, or even sliding doors for closets and shelf-units could all be manufactured from perforated stone plates using the water jet technology.

Or, put another way, a client who designs the entrance to his hotel or office building incorporating representative stone siding or sets up a bathtub of massive stone may also be interested in stone windows.

And: costs of air conditioning would be reduced since the full-power cooling needed for large glass and steel fronts could be turned down.